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Review of Flows Driven by Natural Convection in Adiabatic Shafts.


pdf icon Review of Flows Driven by Natural Convection in Adiabatic Shafts. (2031 K)
Zukoski, E. E.

NIST GCR 95-679; 46 p. October 1995.

Sponsor:

National Institute of Standards and Technology, Gaithersburg, MD

Available from:

National Technical Information Service
Order number: PB96-147897

Keywords:

buoyant flow; heat transfer; high rise buildings; high temperature gases; leakage; smoke; stack effect; natural convection; turbulent mixing

Abstract:

Experimental and analytic studies of the motion of hot gases through vertical shafts under the influence of buoyancy forces, carried out from 1973 to 1976 at the California Institute of Technology, are reviewed. Such flows originate in and have a hazardous effect during accidental fires in facilities that involve vertical shafts. Two mechanisms are primarily responsible for vertical motion of buoyant gas within a building: stack effect and the turbulent mixing process. This review focuses on the turbulent mixing process, where the vertical dimension of spaces of interest is much larger than the horizontal, i.e., relatively tall shafts. Particular emphasis of the work reviewed is on the transient development of the mixing process within the shaft as hot buoyant gas (e.g., smoke) is introduced into the lower part of a shaft, which is at some initial, uniform, and relatively low temperature.